(Image via Twitter)

Sen. John McCain (R-Arizona), a longtime senator and the Republican nominee for president in 2008, has been diagnosed with a cancerous brain tumor.

2 years ago today: Trump declared that John McCain, who spent 5 ½ years as a POW, is “not a war hero … I like people that weren’t captured” pic.twitter.com/Y189mVPsGh

— Bradd Jaffy (@BraddJaffy) July 18, 2017 

He and his family are exploring treatment options.

John McCain is an American hero & one of the bravest fighters I've ever known. Cancer doesn't know what it's up against. Give it hell, John.

— Barack Obama (@BarackObama) July 20, 2017

Just this week, a vote on the eventually DOA repeal and replacement of Obamacare was stalled while John McCain had a blood clot removed from above his left eye.

Also worth noting is Sen. McCain's confused-seeming performance of late, which now feels like an ominous sign of something more wrong than simple sleeplessness.

Well wishes have poured in from all sides of the political spectrum.

Not a fan, but Trump's rise has definitely put that into perspective, and I wish him well. 

John McCain is as tough as they come. Thinking of John, Cindy, their wonderful children, & their whole family tonight.

— Hillary Clinton (@HillaryClinton) July 20, 2017